设计模式之观察者模式_C++

// ADBHelper.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

//#include "pch.h"
#include <stdafx.h>
#include <iostream>
#include <list>
using namespace std;

class Observer
{
public:
    virtual void Update(int) = 0;
};

class Subject
{
public:
    virtual void Attach(Observer *) = 0;
    virtual void Detach(Observer *) = 0;
    virtual void Notify() = 0;
};

class ConcreteObserver : public Observer
{
public:
    ConcreteObserver(Subject *pSubject) : m_pSubject(pSubject) {}

    void Update(int value)
    {
        cout << "ConcreteObserver get the update. New State:" << value << endl;
    }

private:
    Subject *m_pSubject;
};

class ConcreteObserver2 : public Observer
{
public:
    ConcreteObserver2(Subject *pSubject) : m_pSubject(pSubject) {}

    void Update(int value)
    {
        cout << "ConcreteObserver2 get the update. New State:" << value << endl;
    }

private:
    Subject *m_pSubject;
};

class ConcreteSubject : public Subject
{
public:
    void Attach(Observer *pObserver);
    void Detach(Observer *pObserver);
    void Notify();

    void SetState(int state)
    {
        m_iState = state;
    }

private:
    std::list<Observer *> m_ObserverList;
    int m_iState;
};

void ConcreteSubject::Attach(Observer *pObserver)
{
    m_ObserverList.push_back(pObserver);
}

void ConcreteSubject::Detach(Observer *pObserver)
{
    m_ObserverList.remove(pObserver);
}

void ConcreteSubject::Notify()
{
    std::list<Observer *>::iterator it = m_ObserverList.begin();
    while (it != m_ObserverList.end())
    {
        (*it)->Update(m_iState);
        ++it;
    }
}

int main()
{
    // Create Subject
    ConcreteSubject *pSubject = new ConcreteSubject();

    // Create Observer
    Observer *pObserver = new ConcreteObserver(pSubject);
    Observer *pObserver2 = new ConcreteObserver2(pSubject);

    // Change the state
    pSubject->SetState(2);

    // Register the observer
    pSubject->Attach(pObserver);
    pSubject->Attach(pObserver2);

    pSubject->Notify();

    // Unregister the observer
    pSubject->Detach(pObserver);

    pSubject->SetState(3);
    pSubject->Notify();

    delete pObserver;
    delete pObserver2;
    delete pSubject;
}

// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

// Tips for Getting Started: 
//   1. Use the Solution Explorer window to add/manage files
//   2. Use the Team Explorer window to connect to source control
//   3. Use the Output window to see build output and other messages
//   4. Use the Error List window to view errors
//   5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
//   6. In the future, to open this project again, go to File > Open > Project and select the .sln file

转载：https://www.cnblogs.com/carsonzhu/p/5770253.html

未完，待描述……